Well, maybe this is just a sign that he's not ready for it yet. It could be just a matter of a couple of weeks or a month or so. Go back to your old nighttime/naptime situation for a bit, and just very gradually transition him to his toddler bed when you feel he might be ready.
Did you have him with you before? If so, try a mattress at the foot of your bed, and even sleep there with him a few times, or lay there with him till he falls asleep or soon before, as he's drifting off.
Whatever you do, don't force anything. Know that he needs your comfort and to feel secure about sleep. You'll get there! A little patience now will really pay off for everyone in the long term.
I got most of this from the Sears books. Of all the stuff I've read, theirs makes the most sense. They have a whole book called Nighttime Parenting. Might want to get more details by checking it out from your library. I'm sure they have all kinds of suggestions that can help you.
L.